1. Technical Field
The present invention relates in general to joining processes and, in particular, to an improved system, method, and apparatus for swaging together two or more components with shape memory alloys.
2. Description of the Related Art
Swaging is a metal-forming technique in which metals are plastically deformed to their final shape using high pressures, either by pressing or hammering, or by forcing a die through the materials. Swaging differs from forging in that the swaged metal is cold worked, and the output of the swaging operation is usually the finished shape.
In one application, swaging may be used to join together two separate components of metal. During the process, at least one of the components is plastically deformed and pressed against the other to form a joint. Different agents and methods are used for plastic deformation of the metal. For example, in a magnetic hard disk drive, swaging is used to join head gimbal assemblies (HGAs) 11 (FIGS. 1-3) to the actuator arms 13. The suspension portion of the HGA has a base plate 11, which is embossed to produce a tubular element 15. This tubular element 15 is inserted into a hole in the arm 13 and a stainless steel ball 17 of precise diameter is pressed through the hole in the base plate 11. This process is depicted in FIGS. 1 and 2, which show isometric and cross-sectional views through the middle of the actuator arm.
FIG. 3A illustrates the assembly before plastic deformation of tubular part 15 of base plate 11 by ball 17, and FIG. 3B is after plastic deformation of tubular part 15 by ball 17. This deformation is caused by the force exerted by the stainless steel ball 17 and leads to a good contact between the suspension 11 and the arm 13.
One drawback of this method is that motion of the ball causes a shear force on the base plate and can deform it. This deformation can change the mechanical alignment of the disk drive slider with respect to the disk, causing a change in the flying height of the slider relative to the disk. Another complication is encountered during this process when two HGAs are joined to the two opposite sides of the same arm. Since the ball moves in only one axial direction, the deformation it causes can lead to an asymmetry between the suspension joined to the top of the arm and the one joined to the bottom of the arm. Thus, an improved solution that avoids these problems is needed to process these components while minimizing shear forces and eliminating the asymmetry caused by the unidirectional motion of ball.